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Text | The semiconductor industry is vertical
Recently, Huawei's first millimeter wave AI supersensitive sensor was officially unveiled, and it is rumored that Apple's self-developed millimeter wave RF RF chip has also completed the design, codenamed Turaco. MediaTek and China Telecom, a leading telecom company, announced a cooperation on the 7th to create a 5G millimeter wave chip test environment at MediaTek Hsinchu's R&D headquarters.
Because millimeter wave has the three advantages of high transmission rate, large working bandwidth and wide standby space, it can better meet the performance requirements of emerging fields such as AR, VR, and intelligent IoT systems. Major manufacturers began to focus on the study of millimeter wave chips.
What is a millimeter wave chip
Millimeter wave refers to electromagnetic waves with frequencies between 30 GHz and 300 GHz, so named because their wavelengths are in the millimeter range. Compared with the sub-6GHz band, the millimeter wave band has rich spectrum resources, which has a huge advantage in carrier bandwidth, which can realize large-bandwidth transmission of 400MHz and 800MHz, and realize ultra-high-speed data transmission through co-construction and sharing between different operators. At the same time, the millimeter wave wavelength is short, and the required component size is small, which is convenient for the integration and miniaturization of equipment products, which meets the mainstream needs of the current terminal market.
Millimeter wave chips are IC devices that can transmit and receive signals in the millimeter wave band. Because the millimeter wave phased array chip integrates millimeter wave technology and phased array principle, the technical difficulty is high, and in the past it was mainly used in the military field. Thanks to the rapid iteration of 5G and 6G communications, millimeter wave has been able to open up the civilian market and become a major development direction of the global communications industry. Yole expects the AiP and millimeter wave front-end modules to be valued at $2.7 billion by 2026.
The traditional millimeter wave monolithic integrated circuit mainly uses compound semiconductor processes, such as gallium arsenide (GaAs), indium phosphide (InP), etc., which have good performance in the millimeter wave band and are the mainstream integrated circuit processes in the frequency band. On the other hand, in the past ten years, silicon-based (CMOS, SiGe, etc.) millimeter-wave submillimeter-wave integrated circuits have also made great progress.
GaAs and InP millimeter wave chips
With high electron mobility and large drift rate, InP materials are the main choice for stable operation of millimeter wave circuits and terahertz electronic devices. With high frequency, low noise, high efficiency, and radiation resistance, InP base devices have become the preferred material for W-band and higher-frequency millimeter wave circuits.
Compound semiconductor devices represented by GaAs have obvious advantages in high-frequency, high-speed, high-bandwidth and microwave millimeter-wave integrated circuits. At present, the compound semiconductor high-frequency devices and circuit technology represented by gallium arsenide (GaAs) has entered a mature stage and has been widely used in the field of high-frequency communications, especially in the field of mobile communications and optical fiber communications.
Millimeter-wave 5GPA made of second-generation semiconductor GaAs and InP is superior to products made of silicon-based CMOS and can be integrated into RF modules for mobile devices and small 5G batteries.
GaN millimeter wave chip
As a representative of the third generation of wide bandgap semiconductors, gallium nitride (GaN) has the advantages of large bandgap width, high electron mobility and high dielectric strength, and can be widely used in cutting-edge military equipment and civil communication base stations in the microwave millimeter wave band.
In the 5G mmWave RFIC market by 2026, RF transceivers and RFFE are likely to reach $10.4 billion and $23.5 billion in TAMs, respectively.
Japan's Eudyna reported a 0.15 nm gate length GaN power device with a power output density of 13.7 W/mm at 30 GHz. THE AMERICAN HRL has reported a variety of GN-based devices in the E-band, W-band and G-bands, with a power density of more than 2W/mm in the W-band and a power density of 296mW/mm at 180GHz.
Silicon-based millimeter wave chip
Due to the huge advantages of silicon process in terms of cost and integration, the research of silicon-based millimeter wave integrated circuits has become one of the current research hotspots.
With the support of the National 973 Program, the 863 Program and the Natural Science Foundation, research has been rapidly carried out and progress has been made. Based on the 90nm CMOS process, the State Key Laboratory of Millimeter Wave of Southeast University has successfully designed Q, V and W band amplifiers, mixers, VCO devices and devices such as W-band receivers, Q-band multi-channel transceivers, CMOS multipliers to 200GHz and SiGe oscillators to 520GHz.
Millimeter wave chip and 6G relationship
Although the current Sub-6GHz band has been relatively saturated with available space after a period of development, the millimeter wave band has relatively more available space and less interference.
The 5G mmWave chipset includes a baseband processor/modem and RFIC components such as RF transceivers and RF front ends. Mobile devices are a major contributor to the mmWave 5G chipset market due to the increasing availability of 5G mmWave-enabled smartphones and other consumer devices, with 5G mmWave baseband processors installed reaching 3.8 billion by 2026.
Samsung has completed the development of cutting-edge mmWave radio frequency circuits (RFICs) and digital/analog front-end (DAFE) ASICs that will support applications in the 28GHz and 39GHz bands; in 2020, Qualcomm released its third-generation 5G modem-to-antenna solution, the Snapdragon X60. The Snapdragon X60 uses 5G baseband from the 5nm process, but also supports millimeter wave and Sub-6GHz polymerization solutions.
Ren Zhengfei once said: "Huawei's success in 5G technology is because of the centimeter wave; and the millimeter wave of 6G is the general direction." ”
6G networks will support higher peak rates and service capacities, as well as high precision positioning accuracy and micron-level sensing resolution below 10 centimeters. Millimeter waves provide large bandwidths that can effectively improve the resolution of space and distance. In the perception and integration of the Internet in the future, millimeter waves will play an important role.
Millimeter wave chip bottleneck
Because millimeter wave frequencies are high, have distributed parameters, and essentially evolve from the "road" to the field, its design process and testing are more complex.
One is that millimeter wave frequencies make designing and testing more difficult than RF testing below 6GHz.
Signal path losses and impedance mismatches are amplified at higher frequencies and can greatly affect signal fidelity. The total loss of the 6GHz interface board between the cable, PCB and contactor interface will be less than 3 to 5dB, while the loss of the interface board designed to operate at 40GHz on the same signal chain will increase by a factor of 2 to 4.
This makes accurate calibration more difficult, and calibration drift is faster, which has an impact on test results.
High-capacity silicon chips bring millimeter wave testing to the ATE world for the first time. Previous tests were done using desktop equipment and could not cope with the quantities needed in the future. This has led to significant developments in high-frequency RF capabilities that can deliver the cost and throughput required for economical production.
For production testing, the goal is to make good enough measurements at high speeds to maintain high throughput. This means that the trade-offs that are traditionally done in lower quantities are very different.
While radar chips may have 1 to 3 or 4 lines, 5G chips will have 30 lines. Industry insiders said: "With the capacity that a 5G phone might have, they want to test four or eight at a time, so now we're talking about more than 200mm wave lines, and they haven't done any testing before that." ”
Second, the design cost of high-band millimeter wave chips is more expensive.
The higher the frequency band of the millimeter-wave radar chip, the higher the cutoff frequency requirements for the transistor, which requires more advanced process nodes and becomes more expensive. For example, a 65nm CMOS process cutoff frequency, Fmax, can reach 300GHz, which is sufficient for designing radar front-end circuits that operate at 60GHz or 77GHz. If the operating frequency is increased to 140GHz, the design difficulty using the 65nm process will be dramatically increased. The higher the frequency, the higher the signal integrity requirements of the package and the higher the cost of the package. The final choice of frequency band for millimeter-wave radar chips needs to be considered among these factors.
The current situation of millimeter wave chips in China
From the perspective of the global market, there are already a number of 5G chips related to millimeter wave technology on the market. Intel released the XMM80605G multimode baseband chip in November 2017, which supports both the sub-6GHz band and the 28GHz millimeter wave band. Qualcomm has been able to provide the supply of millimeter wave terminal chips X50 and X55, antenna module QTM525.
The maturity of the mainland 5G millimeter wave industry chain lags behind the 5G low frequency, and also lags behind the international advanced level such as the United States and Europe. It is manifested in the single form of millimeter wave equipment, the function and performance do not meet the requirements of 5G networking, and the 5G millimeter wave chip and terminal model are few, and the coverage type and form are not rich enough.
Among them, the obstacles mainly come from high-frequency devices, mainly including: high-speed and high-precision digital-to-analog and analog-to-digital conversion chips, high-frequency power amplifiers, low-noise amplifiers, filters, integrated package antennas and so on.
In terms of policy, in November last year, the Ministry of Industry and Information Technology approved the establishment of a national 5G medium and high frequency device innovation center. Focusing on the major needs of the field of 5G medium and high frequency devices, the center focuses on three major research and development directions, such as new semiconductor materials and processes, 5G medium and high frequency core devices, and silicon-based millimeter wave integrated chips for the RF front end, supporting the innovation and development of the 5G medium and high frequency device industry in mainland China.
In terms of universities, the School of Integrated Circuits of Tsinghua University has developed a millimeter wave Ka-band RF front-end chip applied to satellite communication using the 65nmCMOS process, integrating 8 receive channels or 8 transmission channels on a single chip (as shown in Figure 1), with a single channel transmission output power of more than 12.71dBm, a phase shift accuracy of 6bit, an amplitude control accuracy of 5bit, and a single transmission channel power consumption of 302mW.
Hangzhou Dianzi University has independently developed E-band millimeter wave chips to achieve commercialization, and successfully achieved the world's first high-order millimeter wave field verification in 2018 in deutsche Telekom's field experiments, with a rate of 70GBps. In the commercial tender for 5G millimeter wave mobile base station prototype RF chips, it also beat international manufacturers such as Macom/Triquint/Gotmic and officially became one of Huawei's 5G communication suppliers.
China Electronics 38 has released a high-performance 77GHz millimeter wave chip and module, and its packaged antenna module contains two 38 self-developed 77GHz millimeter wave radar chips, which are oriented to the demand for core millimeter wave sensors in the field of intelligent driving, using low-cost CMOS (complementary metal oxide semiconductor process), and integrating 3 transmission channels, 4 receiving channels and radar waveform generation.
In terms of enterprises, Heertai's subsidiary Chengchang Technology is a private enterprise in the field of microwave millimeter wave T/R chips in China, except for a few national defense research institutes, which master core technologies.
In 2018, Heertai acquired Chengchang Technology and officially entered the millimeter wave RF chip, and Heertai was able to provide the market with a series of products based on GaN, GaAs and silicon-based processes, mainly including power amplifier chips, low-noise amplifier chips, analog beamforming chips and RF switch chips. Products have been used in communications, navigation, detection, remote sensing, electronic countermeasures and other fields. The RF chip for 5G base stations has completed the chip development work; the satellite Internet RF chip has been delivered in small batches.
Since it was incubated and independent from the Shanghai Microtechnology Industry Research Institute in 2016, Shanghai Silicon Jie Microelectric has been committed to the development of millimeter wave radar chips, and has been deeply involved in the application of millimeter wave radar sensors in the consumer field, industrial field, and automotive field. In 2017, it developed the first highly integrated 24GHz radar SoC with independent intellectual property rights in China, and currently has a series of 24GHz and 77GHz millimeter wave radar chips.
Yaguang Technology "5G millimeter wave communication multi-function chip research" project is a major scientific and technological project in Sichuan Province, the company's millimeter wave power amplifier for communication has been successfully developed.
Shenglu Communications has developed a leading 28G and 64-unit millimeter wave active phased array in China, and has made corresponding array antenna development in 39G, 60G and 80G.
ZTE is based on the exploration of RIS millimeter wave, and in terms of 6G, the current ZTE is based on RIS millimeter wave, and has carried out the exploration of RIS block coverage scene. Experiments have shown that the effective coverage of the non-RES scenario limits the effective coverage, while the coverage is enhanced and expanded when the RIS is increased.
Micro-core micro-research and development of millimeter wave radar chip and micro-system technology, its main products are SiCMOS millimeter wave radar SOC chip, IoT low-power RF transceiver chip, GSM/TD-SCDMA terminal power amplifier chip.
AskTech develops microwave millimeter wave system-on-chip (SoC), the main products include 77GHz automotive radar transceiver RF front-end chip, 60GHz silicon-based SoC transceiver chip, 122GHz mixed-signal radar SoC (also known as terahertz mixed-signal radar SoC), microwave millimeter wave transceiver SoC; 5G mobile communication 28GHz phased transceiver front-end set and other microwave millimeter transceiver phased multi-function chips.
With the gradual popularization of 5G, 6G and satellite communications have begun to slowly enter the public's attention. Millimeter wave as the main role of this will not be absent. But millimeter waves still face many challenges. Ding Haiyu, director of the Institute of Wireless and Terminal Technology of China Mobile Research Institute, believes that the challenges faced by 5G millimeter wave are that the network performance is not mature enough; the second is that the cost is not low enough; the third is that the network industry collaboration is not deep enough; and the fourth is that the end-to-end standardization is not fast enough.
To do a good job in 5G, 6G can be done, and the development of millimeter wave also needs to strengthen industry-university-research cooperation and jointly promote the maturity of the millimeter wave industry.